How does the food stay crispy?

I quite like dishes like pan-fried chicken nuggets, Chicken Kijiyaki (tomorrow's bento ^^), Chicken Kara-age or the Fried Shrimp as the meaty part of my bentos... But somehow the fried foods never stays crispy after a few hours in a bento box. I always let everything cool down completely before I put it in the box or before I close the lid but still... I mean, I don't expect my chicken to be super crispy, but it would be nice if it had a little crunch instead of being a little soggy. Does anybody have a trick? Maybe I am doing something wrong?

On a different note, I love this purple powder that comes on the rice in some Japanese restaurants. I think it's the same stuff I see in the pictures of Toyama's bentos (the one in the bright blue boxes from the "Great Bento Ideas: One box, infinite bentos" article). I really like this "powder", can you please let me know what it is called or what's in it? They have different rice seasonings in the Japanese Grocery store I go to, but I don't know which one to buy.

I mean to address the fried food/crispy thing later on in a full article so please be patient ^_^ (short answer though is, no it doesn't stay crispy unless you use specific foods for the coating.) The purple powder - is it a bit sour/salty? Then it's yukari, which are the dried red shiso leaves that are a byproduct of making umeboshi. The salty sour leaves are dried and ground up into a powder. You can get yukari at any Japanese food store.

I also really really want to know how to make it stay crispy - even when I follow the recipes (which I assume have the right coating...??), they're soggy by lunchtime. It makes it *so* hard to resist eating my lunch the minute it comes out of the pan in the morning. :)